diff --git a/esphome/components/mdns/__init__.py b/esphome/components/mdns/__init__.py
index 12ec7353b5..ce0241677d 100644
--- a/esphome/components/mdns/__init__.py
+++ b/esphome/components/mdns/__init__.py
@@ -18,6 +18,8 @@ CODEOWNERS = ["@esphome/core"]
 DEPENDENCIES = ["network"]
 
 # Components that create mDNS services at runtime
+# IMPORTANT: If you add a new component here, you must also update the corresponding
+# #ifdef blocks in mdns_component.cpp compile_records_() method
 COMPONENTS_WITH_MDNS_SERVICES = ("api", "prometheus", "web_server")
 
 mdns_ns = cg.esphome_ns.namespace("mdns")
diff --git a/esphome/components/mdns/mdns_component.cpp b/esphome/components/mdns/mdns_component.cpp
index 6dba821258..58952e94e9 100644
--- a/esphome/components/mdns/mdns_component.cpp
+++ b/esphome/components/mdns/mdns_component.cpp
@@ -75,6 +75,9 @@ void MDNSComponent::compile_records_() {
   this->hostname_ = App.get_name();
   this->services_count_ = 0;
 
+  // IMPORTANT: The #ifdef blocks below must match COMPONENTS_WITH_MDNS_SERVICES
+  // in mdns/__init__.py. If you add a new service here, update both locations.
+
 #ifdef USE_API
   if (api::global_api_server != nullptr) {
     auto &service = this->services_[this->services_count_++];